1. Field
One embodiment of the present invention relates to a magnetic recording media having discrete tracks, a substrate used to manufacture the magnetic recording media, and a magnetic recording apparatus comprising the magnetic recording media.
2. Description of the Related Art
With an increase in the track density of hard disk drives (HDDs), interference between adjacent tracks has become more and more problematic. In particular, an important technical objective is to reduce write fringing caused by the fringe effect of a magnetic field from the write head. A discrete track type patterned media (a DTR media) with physically separated recording tracks can reduce a side erase phenomenon during data writing and a side read phenomenon during data reading, making it possible to greatly increase density in the cross-track direction. The discrete track type patterned media is thus expected to provide a magnetic recording media that can realize high-density recording.
The DTR media is roughly classified into a magnetic film etching type and a substrate etching type. The magnetic film etching type DTR media involves a large number of manufacturing steps and is expected to increase costs. In contrast, the substrate etching type DTR media, which is manufactured by first forming protrusions and recesses in the substrate and then depositing a magnetic film on the substrate by sputtering, is suitable for mass production.
However, because the magnetic film is also present in recesses in the substrate etching type DTR media, the signal-to-noise ratio may disadvantageously be degraded due to magnetic signals from the recesses.
A HDD media has been known in which protrusions and recesses are formed on a surface of a substrate and in which a magnetic film is deposited on the protrusions and recesses substrate (see U.S. Pat. No. 5,402,278). In the HDD media, data are recorded to the magnetic film on the protrusions located close to the head. The magnetic film on the recesses is located away from the head and is thus not subjected to magnetic recording. The magnetic film on the recesses also provides low read signals. The HDD media is intended to suppress the recording interference between adjacent tracks. However, with U.S. Pat. No. 5,402,278, the large depth of the recesses in the surface of the media makes it difficult to allow the read/write head to fly stably over the media having the protrusions and recesses.
On the other hand, a method has been proposed in which a magnetic multilayer film is deposited on a flat substrate surface and the magnetic multilayer film in the regions between tracks is irradiated with ion beams for destroying the structure (see U.S. Pat. No. 6,331,364). This method degrades the magnetic recording characteristics of the magnetic material between the tracks, which is not subjected to magnetic recording. The magnetic material between the tracks also provides weak read signals. This method is intended to suppress the recording interference between the adjacent tracks. However, U.S. Pat. No. 6,331,364 essentially requires the ion-beam irradiation process after deposition of the magnetic film, leading to higher costs for manufacturing the media.